--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cubicweb/server/cwzmq.py	Sat Jan 16 13:48:51 2016 +0100
@@ -0,0 +1,130 @@
+# -*- coding: utf-8 -*-
+# copyright 2012-2014 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
+#
+# This file is part of CubicWeb.
+#
+# CubicWeb is free software: you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation, either version 2.1 of the License, or (at your option)
+# any later version.
+#
+# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
+
+from threading import Thread
+from logging import getLogger
+
+import zmq
+from zmq.eventloop import ioloop
+import zmq.eventloop.zmqstream
+
+from cubicweb import set_log_methods
+
+
+ctx = zmq.Context()
+
+
+class ZMQComm(object):
+    """
+    A simple ZMQ-based notification bus.
+
+    There should at most one instance of this class attached to a
+    Repository. A typical usage may be something like::
+
+        def callback(msg):
+            self.info('received message: %s', ' '.join(msg))
+        repo.app_instances_bus.subscribe('hello', callback)
+
+    to subsribe to the 'hello' kind of message. On the other side, to
+    emit a notification, call::
+
+       repo.app_instances_bus.publish(['hello', 'world'])
+
+    See http://docs.cubicweb.org for more details.
+    """
+    def __init__(self):
+        self.ioloop = ioloop.IOLoop()
+        self._topics = {}
+        self._subscribers = []
+        self.publisher = None
+
+    def add_publisher(self, address):
+        assert self.publisher is None, "more than one publisher is not supported"
+        self.publisher = Publisher(self.ioloop, address)
+
+    def add_subscription(self, topic, callback):
+        for subscriber in self._subscribers:
+            subscriber.subscribe(topic, callback)
+        self._topics[topic] = callback
+
+    def add_subscriber(self, address):
+        subscriber = Subscriber(self.ioloop, address)
+        for topic, callback in self._topics.items():
+            subscriber.subscribe(topic, callback)
+        self._subscribers.append(subscriber)
+
+    def publish(self, msg):
+        if self.publisher is None:
+            return
+        self.publisher.send(msg)
+
+    def start(self):
+        Thread(target=self.ioloop.start).start()
+
+    def stop(self):
+        self.ioloop.add_callback(self.ioloop.stop)
+
+    def __del__(self):
+        self.ioloop.close()
+
+
+class Publisher(object):
+    def __init__(self, ioloop, address):
+        self.address = address
+        self._topics = {}
+        self._subscribers = []
+        self.ioloop = ioloop
+        def callback():
+            s = ctx.socket(zmq.PUB)
+            self.stream = zmq.eventloop.zmqstream.ZMQStream(s, io_loop=ioloop)
+            self.stream.bind(self.address)
+            self.debug('start publisher on %s', self.address)
+        ioloop.add_callback(callback)
+
+    def send(self, msg):
+        self.ioloop.add_callback(lambda:self.stream.send_multipart(msg))
+
+
+class Subscriber(object):
+    def __init__(self, ioloop, address):
+        self.address = address
+        self.dispatch_table = {}
+        self.ioloop = ioloop
+        def callback():
+            s = ctx.socket(zmq.SUB)
+            self.stream = zmq.eventloop.zmqstream.ZMQStream(s, io_loop=ioloop)
+            self.stream.on_recv(self.dispatch)
+            self.stream.connect(self.address)
+            self.debug('start subscriber on %s', self.address)
+        ioloop.add_callback(callback)
+
+    def dispatch(self, msg):
+        try:
+            f = self.dispatch_table[msg[0]]
+        except KeyError:
+            return
+        f(msg)
+
+    def subscribe(self, topic, callback):
+        self.dispatch_table[topic] = callback
+        self.ioloop.add_callback(lambda: self.stream.setsockopt(zmq.SUBSCRIBE, topic))
+
+
+set_log_methods(Publisher, getLogger('cubicweb.zmq.pub'))
+set_log_methods(Subscriber, getLogger('cubicweb.zmq.sub'))